In a prior art of a nut supply apparatus to a spot welding machine, for example, a nut send-out port is provided at a terminal end of a supply chute inclined downward so that a plurality of nuts may be supplied continuously in parallel in a same direction, at a front end of a guide rod disposed movably back and forth in an oblique downward direction while intersecting with the nut send-out port, and a holding pin for piercing and holding through the nuts is protruded while penetrating through screw holes of the nuts supported at the nut send-out port, and when the guide rod moves forward in an oblique downward direction, and the leading end of the holding pin approaches and moves to a bonding position of a bonding machine, the nuts held on the holding pin are supplied by fitting with a positioning pin provided at the bonding position (see Patent Literature 1, 2).
Applications of the weld nuts supplied by this conventional nut supply apparatus are mainly in the automobile industrial fields, and the nominal size of nuts was mainly in a range of M6 to M12. Accordingly, the diameter of the holding pin for holding the nuts by penetrating through the screw holes of the nuts was relatively large, and there was no problem in fitting of the nuts with the positioning pin due to fluctuations of the leading end of the holding pin.
However, when the nominal size of the nuts to be supplied is as small as about M1.6, the hole diameter of the screw hole is as small as about 1.0 mm, the holding pin is also thin, fitting of the nuts with the positioning pin at the welding machine side may be difficult due to fluctuations of the leading end of the holding pin. Since this type of the nut supply apparatus is, moreover, mounted on a stand installed near the welding machine, if vibrations in the factory are transmitted to the welding machine side or the stand side, the leading end of the holding pin may fluctuate slightly due to the vibrations, and it may cause a problem in fitting of the nuts with the positioning pin due to fluctuations of the leading end of the holding pin.